[OSM-talk] New tool in Potlatch 2 for areas that share a way

[Anthony]

On Mon, Jan 31, 2011 at 11:02 AM, M∡rtin Koppenhoefer
<dieterdreist at gmail.com> wrote:
> 2011/1/31 Matt Williams <lists at milliams.com>:
>> The example that come to my mind is the case where an administrative
>> boundary is _defined_ by a river or stream for example.
>
>
> Yes, the same came to my mind. But what is the situation if the river
> changes? Will the boundary change, or will the boundary be at the
> position of the river at the time when the boundary was defined? IMHO
> probably the latter, which is an argument to keep them separate.

I think the general rule is that changes due to gradual natural causes
change the boundary, but if the changes are due to avulsion, the
boundary remains at the original position.

There's also the fact that a river or stream is not a single line.
While a boundary might be determined as the deepest part of of the
river or stream, the more common location to map the river or stream
would be in the geographical center, which may or may not be the
deepest part.

I'd say in general it's usually better to keep them separate, but my
main point was just that *sometimes* it's better to keep them
separate, even if they are initially drawn in the exact same location.